1. Field of the Invention
The present invention relates to armaments and more particularly to guided munitions. Even more particular, the invention relates to an optical homing tag for guiding the muntions to a target.
2. Background Information
Mortars and other forms of indirect munition fire are one of the most commonly employed weapons in a ground combat unit. Large guided munitions have been successfully developed and deployed but have generally required expensive vehicular platforms (fixed wing or rotary aircraft) or large caliber guns (ships or mobile howitzers) to deliver the munitions. These platforms and delivery systems may not be available to ground combat units, whose speed, mobility and agility contribute to their survivability. It is now feasible to miniaturize small caliber guidance and designation systems such that maneuverable ground combat units can be armed with precision guidance weapons.
Ground combat units commonly have small caliber armaments, including rifles, grenade launchers and mortars. Rifles are accurate direct-fire weapons, but challenging to integrate guidance or homing tags due to their small caliber (typically 5.66 mm or 223 caliber). Future improvements in power-density and electrical-to-radiated conversion efficiency may permit bullets to be used as homing tags. Presently, grenade launchers (20 and 40 mm) are large enough to integrate electronics and power supplies for homing devices. They are considered direct-fire, hence their placement accuracy is relatively good against targets. But they lack the volume to carry sufficient explosives to effect large areas or hardened targets. Conversely, mortars are indirect fire weapons which carry relatively large explosives and have sufficient volume for guidance capabilities.
The traditional role of mortars has been to provide close and continuous fire support for maneuvering forces. Military history has repeatedly demonstrated the effectiveness of mortars. Their rapid, high-angle, plunging fires are invaluable against dug-in enemy troops and targets in defilade, which are not vulnerable to attack by direct fires. One of the major disadvantages of mortars is their comparatively low accuracy, and as a result mortars are becoming less effective in today's precision combat environment. Equipping a mortar round with a precision guidance package will increase its accuracy, enabling the mortar to be a precision munition that will be significantly more effective in wartime situations. For maximum utility, the guidance package preferably should be an inexpensive retrofit to current munitions, with a cost in production that allows its use in all situations, either as a guided or unguided weapon.
Unguided munitions are subject to aim error and wind disturbances. These factors, along with other more subtle error sources, may cause the munition to miss the target completely or require many rounds to complete the fire mission due to the resulting large CEP (Circular Error Probability). Current approaches to guided weapons are expensive and are used on larger, long range weapons. The approach of the present invention disclosure results in significantly lower cost and smaller size. This allows use with small to medium caliber weapons and significantly improves CEP which also results in a significant reduction in the quantity of rounds required to complete the fire mission which in turn results in lower overall cost and improved crew survivability. In addition, another benefit to this approach is the virtual elimination of collateral damage due to errant rounds impacting non-targeted areas. Furthermore, complete integration of a seeker/guidance error can be used in a modification to the existing fuse in order to “safe” errant rounds which are failing to meet an established CEP ground rule which further controls unwanted collateral damage by preventing detonation of off target rounds.
Mortars are typically unguided or guided by an expensive G&C (Guidance and Control) system. The cost is high for current guided mortars and unguided mortars may have poor accuracy. Also, unguided mortars may result in unacceptable collateral damage, excess cost due to the large number of rounds required to blanket the target area, and may expose the mortar crew to counterbattery fire due to the large time required to drop the necessary shells to saturate the target.
One manner of guiding the munitions to a target is to provide a guidance signal for reception by a guidance and control assembly mounted in the nose of the munitions wherein the guidance signals emanate from an optical designator which is located at the target. This optical designator can be provided by a stand off illuminator which is aimed at the desired impact point of the target by a forward observer or by a manned or unmanned aircraft flying close to the target.
Although these various types of optical designators are satisfactory in certain respects, they have certain drawbacks in that it requires a forward observer to be close enough to the target to place the optical designator on the target such as by a laser beam, and requires that he has possession of the needed equipment. Also, this placement requires that the forward observer be close to the target which could alert the enemy at the target site of his presence and also result in injury to the forward observer. Thirdly, the forward observer must designate the target for a period of time, making themselves in turn open to detection or hostile attack. Other methods would require the need to have a plane in the air near the target, which again would alert the enemy at the target of an attack, possibly resulting in countermeasures being exerted on the forward observer and/or plane. Another type of optical designator can be an optical tag which is placed by some means at the target site. It is difficult to secretly place an optical designator at the target which would remain undetected by the occupants of the target until the munition is ready to be launched.
Therefore, there is a need for an accurate and cost effective target designator, and in particular a homing tag which can be placed at the target in a simple, effective manner by a soldier from a relatively safe distance just prior to launching of the munition to be guided thereby, which optical tag can be launched in a simple and effective manner by known types of munition launchers.